Electric motors of the mentioned type are applied for the most varied of purposes and are on the market in comprehensive constructional designs. In particular, such electric motors are also applied as drive motors for centrifugal pumps and are then often designed as a canned motor, wherein the rotor runs in a can filled with fluid, and the can is filled for example with the delivery fluid of the pump, and a part flow of the delivery flow flows through this can.
With electric motors, it is common for these to comprise a so-called terminal box, i.e. a connection housing which is arranged outside on the motor housing and which receives electrical connections as well as electronic components. With electric motors, it is counted as belonging to the state of the art, to arrange such a connection housing peripherally with respect to the motor axis or also axially, i.e. at an end-side of the motor. Connection housings are also known, which extend peripherally as well as on the end-side, e.g. with the heating circulation pumps marketed by Grundfos under the name Magna type 32-60. Thereby, the connection housing typically serves for connecting the motor windings to the electric supply mains, thus for connecting the motor to the supply mains as well as for receiving electronic components. In the simplest case, these can be suppression capacitors or likewise. With modern motors, this connection housing mostly yet comprises motor electronics. This on the one hand can be power electronics, and on the other hand microprocessors, and the electronic components which are common in the context of digital signal processing. In particular, with modern motors controlled by frequency converter, as are regularly applied nowadays with centrifugal pumps but also with other drive applications, it is counted as belonging to the state of the art, to arrange the frequency converter electronics completely or partly in the connection housing.
It is particularly the case when the power electronics are arranged in the connection housing, that it is necessary to effectively and securely lead away the waste heat arising in the housing. In order to ensure this, the connection housings of the known construction type are mostly designed of metal and are provided with cooling ribs, or however the power electronics are cooled via a cooling body arranged outside on the housing or by way of other suitable cooling measures. These cooling bodies require a lot of space and increase the dimensions of the electric motor. It is often problematic that heat-sensitive components also need to be arranged in the connection housing. The design of the housing or housing part of metal is complicated and extensive. Different housings are always necessary for different power sizes and connection housing variants, which requires quite some effort with regard to manufacture, tooling and storage.